ABSTRACT - OVERALL Total joint arthroplasty (TJA) is the most common and fastest growing surgery in the nation. There are currently more than 7 million Americans living with artificial joints. Despite the high surgery volume, the evidence base for TJA procedures, technologies and associated interventions are limited. Many surgical approaches and implant technologies in TJA are adopted based on theoretical grounds with limited clinical evidence. The wider TJA research community needs access to large, high quality and rich data sources and state-of-the-art clinical research standards and information technologies to overcome methodological and practical challenges in studies of surgical and nonsurgical interventions in TJA. The overarching goal of Mayo Core Center for Clinical Research in Total Joint Arthroplasty (CORE-TJA) is to facilitate innovative, methodologically rigorous and interdisciplinary clinical research that will directly improve TJA care and the outcomes. The CORE-TJA will serve as a disease (TJA) and theme-focused Center providing shared methodological expertise, education and data resources. The CORE-TJA will leverage big data resources for TJA research, provide customized methodology resources in epidemiology, biostatistics, health services research and medical informatics, and establish synergistic interactions around an integrated Core (American Joint Replacement Registry ? AJRR). The Specific Aims of CORE-TJA are: (1) To provide administrative and scientific oversight of CORE-TJA activities (Administrative Core), (2) To provide integrated services, access to large databases and novel analytical methods for clinical research in TJA (Methodology Core); and (3) To meet the unique data needs of the TJA research community and to strengthen the national capacity for large-scale observational and interventional studies in TJA using national registry data (Resource Core). The CORE-TJA will be integrated within the long-standing and highly centralized clinical research environment of the Mayo Clinic, thereby leveraging existing expertise and infrastructure resources, including the Center for Clinical and Translational Science. All CORE-TJA activities will be evaluated using robust metrics to ensure continuous evaluation, flexibility and improvement in response to the most pressing needs of the TJA research community.